Network traffic directed to dark address space of IPv4 protocol can be a good source of information about current state of the Internet. Despite the fact that no packets should be sent to such addresses, in practice various traffic types can be observed there, for example echoes of Denial of Service (DoS) attacks, automated port scanners or misconfiguration of some client software. Often the packets are sent periodically, i.e. in regular intervals. This periodicity can be analyzed by applying the Discrete Fourier Transform (DFT) to the network traffic. Our report shows how such analysis can be performed and also its results. You can read the report here.